Indoor air quality is one of the most over-marketed corners of the HVAC world. UV lights, ionizers, ozone generators, and "whole-home purifiers" sell well because they sound technical. Most don't materially change the air in your home.
What actually works
A properly sized, well-sealed filter at the right MERV rating. Reasonable humidity. Source control. For households with specific medical needs, HEPA portable units in bedrooms. That's most of it.
In this pillar
MERV Ratings Explained
The number on the filter doesn't mean what most homeowners think.
Is Duct Cleaning Worth It?
Sometimes yes, often no. Here's the honest answer.